The Scientific Core is intended to serve as a central resource for imaging techniques applied to brain and trigeminal ganglion sections from rats and guinea pigs, as well as from post mortem human tissue. The first project will use receptor autoradiography to detect 5-HT 1D-like and GABA receptor binding sites ina the trigeminal system of rodents and post mortem human brain, as well as in situ hybridization to detect the corresponding messenger RNA's. The second project will use [14C]2-deoxyglucose autoradiography technique to measure regional glucose utilization as an indicator of neuronal activation in the rat brain after painful dural stimulation. Neuronal activation will also be assessed in the same animals (in consecutive brain sections) by detecting the messenger RNA of the early gene c-fos using in situ hybridization. Using the same stimulus, we will use [14C]iodoantipyrine autoradiography in another set of animals to determine the consequences of noxious meningeal stimulation on metabolism/blood flow coupling. The results of such experiments may impact on the interpretation of functional activation studies as an aim of the last project.